Method for dispensing powder with cleansing of dispensing apparatus



Aug. 8, 1967 s. A. LOPENSKI ETAL 3,335,024

METHOD FOR DISPENSING POWDER WITH CLEANSING OF DISPENSING APPARATUS Filed Oct. 1, 1962 ,2 Sheets-Sheet A T0 EXHAUST SYSTEM I I I.

A DRUM SMOKE FEED PINCH- CLAMP VALVE 40 FROM POWDER SMOKE GENERATING VENTURI 48 EXPANSION CHAM BER 38 MOKE E E ATOR.

RECLAIM PlNCH ""CLA'MP VALVE 42 49 INVENTORS.

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METHOD FOR DISPENSING POWDER WITH CLEANSING OF DISPENSING APPARATUS Filed Oct. 1, 1962 2 Sheets-Sheet f.

VERTICAL CLQSED l oA-nN INVENTORS 78 JTfl/VLEY H. ZUPE/VS/F/ EDWHRD J: 6572. BY

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OPEN

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BLOW BECK i CLGSEDI E i O'P'EN MANIFOLD TlLTED FIG. 4.

LOAD 8 UNLOAD INDEX AIR COATING comma NOZZLE CHUCKS CLEANSNG A'R SMOKE FEE-D PINCHCLAM RECLAIM PINCH VALVE COATING FIRES FlG.9.

United States Patent 01 3,335,024 METHOD FOR DISPENSING POWDER WITH CLEANSING OF DISPENSING APPARATUS Stanley A. Lopenski, Pompton Plains, and Edward J. Getz,

'Irvington, N.J., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 1, 1962, Ser. No. 227,489 6 Claims. (CI. 117--66) This invention relates to a method and apparatus for dispensing powder which is carried as a smoke in a gaseous stream and, more particularly, to an improved method and apparatus for dispensing powder to a plurality of coating heads which operate in conjunction with an electrostatic coating machine for coating incandescent lamp bulbs.

An electrostatic coating machine for coating incandescent lamp bulbs is generally described in U.S. Patent No. 2,811,131, dated October 29, 1957. In order to speed up production of such coated bulbs, improved machines have been designed to coat a plurality of bulbs simultaneously, and such a machine is described in U.S. Patent No. 3,017,852, dated January 23, 1962. When coating a plurality of bulbs simultaneously, it is desirable to uti lize only one smoke-generating apparatus in order to obtain a uniform coating on all bulbs. When operating such an apparatus, however, some production difficulties have been encountered in maintaining the coating lines free from a build-up of residual, uncoated powder, and in maintaining a substantially uniform appearance of the coating on all bulbs which are simultaneously coated. In addition, troubles have been encountered with deposition on the bulbs of overly large particles or particle agglomerates, which give the finished coating a grainy appearance. In some cases, this has resulted in a rejection of finished lamps for imperfect coatings.

It is the general object of this invention to provide an improved method for simultaneously and uniformly distributing coating powder to a plurality of coating positions and preventing any build-up of residual powder in the coating lines.

It is another object to provide an improved apparatus which will remove from a coating smoke all undesired large particles, and which apparatus will prevent the accumulation of any residual, uncoated powder in the coating supply conduits.

It is an additional object to provide an improved smoke distribution manifold for distributing a smoke of finely divided particles to a plurality of distribution conduits.

It is a further object to provide construction details for an apparatus which will prevent any build-up of residual, uncoated powder in the coating lines and which will remove undesired, large particles from a particle smoke.

The aforesaid objects of the invention, and other objects which will become apparent as the description proceeds, are achieved by providing a smoke expansion chamber which is separated from the smoke generating apparatus. A series of valves connect to the expansion chamber to facilitate cleaning out both this chamber and the coating lines. During the coating operation, a valve positioned at the bottom of the expansion chamber is closed, and the powder smoke is circulated through the expansion chamber, and then through a powder distribution manifold to the individual coating heads. On circulation through the expansion chamber, the larger, undesired particles or particle agglomerates collect in the bottom portion of the expansion chamber. Between each coating cycle, cleansing or blow-out air is introduced at the top portion of the expansion chamber and the valve at thebottom of the expansion chamber is opened, so that all coating material which has accumulated at 3,335,024 Patented Aug. 8, 1967 "ice ' from these conduits and coating nozzles. The valve at the top of the expansion chamber then opens and a stream of cleansing or blow-out air is forced from a blowback manifold and into the coating nozzles, and then through the coating distribution conduits and the expansion chamber. The change of direction of the cleansing air, first out of the nozzles and then into the nozzles, creates a gas-scrubbing action which insures that all residual particles are removed from the distribution conduits and the coating nozzles.

For a better understanding of the invention, reference should be had to the accompanying drawings wherein:

FIGURE 1 is an elevational view, partly schematic and partly in section, showing the improved coating apparatus of the present invention as combined with an electrostatic coating machine;

FIG. 2 is a fragmentary sectional view of the coating nozzle as is shown in FIG. 1;

FIG. 2a is a fragmentary view, partly in section, showing the final gas-cleansing operation wherein the blowback manifold is positioned above the coating nozzle;

FIG. 3 is a view taken on the lines IIIIII in FIG. 1, in the direction of the arrows, showing the powder distribution manifold and the upper pinch clamp valve;

FIG. 4 is a sectional view taken on the lines IV-IV in FIG. 3, in the direction of the arrows, showing construction details for the pinch clamp valve, and the positioning of this valve during the coating operation;

FIG. 5 is a sectional view taken on the lines VV in FIG. 4, in the direction of the arrows, showing construction details for the powder distribution and cleanout manifold;

FIG. 6 is a view similar to FIG. 4, but showing the initial stage of the powder clean-out operation;

FIG. 7 is a view similar to FIG. 4, but showing a later stage of the powder clean-out operation;

FIG. 8 is a timing diagram showing the sequence of operations of the components comprising the present apparatus; and

FIG. 9 is a schematic view showing the operation of one of the solenoids and the associated cam which is used to control the flow of operating air in the present apparatus. The present'invention is particularly adapted for use with an electrostatic coating machine wherein a plurality of bulbs are to be simultaneously coated from o'ne'smoke generator, and such an apparatus embodiment has been illustrated and will be described. It should be understood, however, that the present invention can be used whenever a powder smoke is to be distributed uniformly to a plurality of dispersing nozzles, and the present invention can also be used to dispense powder to only one powder dispersing nozzle.

The electrostatic coating machine 'The electrostatic coating machine 10, as shown in FIG. 1, is generally similar to that machine described in the aforementioned U.S. Patent 3,017,852, and this patent should be referred to for details. Briefly, the uncoated bulbs 12 are loaded by a conventional transfer device 14 from a conveyor head 16 which is carried by a continuous chain conveyor 18, and onto a hollow coating chuck 20. A coating nozzle 22, shown in detail in FIG. 2, is then reciprocated into the hollow coating chuck 20 so as to extend into the interior portion of the loaded bulb 12. Coating fires applied from an electrically grounded, gasair burner 24 heat each bulb 12 to render it substantially uniformly electrically conductive, as is required for electrostatic coating. -A smoke of coating material, which comprises finely divided silica suspended in an air stream, is then introduced into the bulb 12 through the coating nozzle 22 and simultaneously, a unidirectional, highvoltage potential is applied through conductor 26, spring connector 28, and the probe 30. This causes the finely divided silica to deposit on the interior surface of the bulb wall. After coating, the bulbs 12 are loaded back onto the heads 16 carried by the indexable conveyor 18 and indexed to the next fabricating operation.

During the coating operation, the coating chuck 20 is rotated With respect to the coating nozzle 22 to facilitate an even deposition of the coating material onto the bulb 12. This rotation is effected by a worm and driven gear arrangement 32. Between coating operations, each coating head 33, which includes the coating chuck 20, is tilted to facilitate cleaning the coating lines. A coating head assembly 33 is shown in tilted position in dotted lines in FIG. 1. The tilting and rotating mechanism for each coating head 33 are both described in detail in the aforementioned Patent No. 3,017,852. In addition, while only one coating head assembly is shown in detail in FIG. 1, and the other five head assemblies are shown schematically, all six coating head assemblies are similar.

Smoke dispensing apparatus The improved smoke dispensing apparatus 34 is generally shown in FIG; 1, and comprises a smoke generator 36, an expansion chamber 38, a smoke feed pinch clamp valve 40, reclaim pinch clamp valve 42, reclaim powder venturi 44, and the necessary air supply conduits and associated solenoids and valves as are required to control the air fiow to the components which comprise this powder dispensing apparatus.

The smoke generator 36 is generally conventional and comprises a receiving reservoir 46 which feeds powder to a smoke-generating venturi 48. The venturi 48 operates on dry, high-pressure air controlled by solenoid-actuated valve 49. The formed smoke is fed through a feed conduit 50 and the gaseous stream expands into the expansion chamber 38 which has a volume considerably greater than that of the feed conduit 50. The smoke impinges upon the inner wall of the expansion chamber 38 and is circulated therein. At this phase of the operation, the reclaim pinch clamp valve 42 is closed and the smoke feed pinch clamp valve 40 is open. Large particles which are not desired to be coated settle to the bottom portion of the expansion chamber 38 and the remainder of the particles comprising the smoke are forced through and traverse the open pinch clamp valve 40 and are distributed through the six individual smoke delivery conduits 52 to the coating nozzles 22. This operation is shown in FIGURE 4. Pinch clamp valves The pinch clamp valves 40 and 42 are generally similar to those disclosed in US. Patent No. 2,884,895, dated May 5, 1959. Referring to FIGS. 4, 6 and 7, these pinch clamp valves each comprise a housing 54 which surrounds a hollow resilient member 56. Air conduits 58 and 60, shown in FIG. 1, respectively open into the housings of the pinch clamp valves 40 and 42. When high-pressure air is introduced through the conduits 58 or 60, this closes the respective pinch clamp valves by collapsing the hollow resilient members 56. The valve 40 in closed position is shown in FIG. 7.

Smoke distribution manifold The smoke distribution manifold 62, which is fixed to the outlet portion of the pinch clamp valve 40, is shown in detail in FIGS. 3, 4 and and generally comprises a housing 64 having six apertures 66 drilled therethrough and terminating in nipples 68 to which the smoke distribution conduits 52 are attached. The apertures 66 open into the interior surface of the housing 64 to form a generally circular pattern of openings. A deflecting cone 69 forms a part of the interior surface of the housing 64 and is positioned in the center portion of the generally circular pattern formed by the apertures 66 provided through the interior surface of the housing 64. The apex portion of the deflecting cone 69 extends into the interior of the housing 64 and in an opposite direction to that of the gaseous stream which carries the smoke to be distributed. The deflecting cone 69 thus serves to deflect the gaseous stream carrying the smoke of particles so that each of the apertures 66 receive a uniform amount of the smoke to be deposited.

The distribution manifold 62 also includes a cleansing air aperture 70 opening through the center portion thereof and terminating in individual apertures 72 which open into the distribution manifold proximate to the inlet side of each of the apertures 66. A cleansing air conduit 73 connects to the aperture 70 provided through the manifold 62.

A ball-check valve 74, spring loaded to a closed position, is provided in the cleansing air conduit 73, in order to prevent powder build-up in this conduit during the coating operation.

The cleansing air is supplied from a dry air supply source so as not to introduce moisture into the expansion chamber and the coating conduits. As a specific example, the dry air is supplied to the apparatus at a pressure of 50 psi. and at a dew-point temperature of from minus 20 F. to minus 40 F. The air which is supplied to operate the pinch clamp valves 40 and 42 is supplied to the apparatus as a pressure of 40 p.s.i.

Operation of the individual, solenoid-actuated valves which are associated with the apparatus is accomplished by cams which open and close the switches to the individual solenoids. In FIG. 9 is shown a solenoid-actuating cam 76 which closes switch 78' to actuate the solenoid 80, which in turn opens valve 82 (see FIG. 1) to admit cleansing air through the conduit 73 to the distribution manifold 62. The other solenoid-actuated valves operate in similar fashion.

Operation of the machine Referring to FIG. 8, which illustrates the machine operation timing sequence, the uncoated bulbs 12 are first indexed into position adjacent to a coating head 20. During index, the coating heads 20 are tilted, as shown in dotted lines in FIG. 1, to facilitate the cleaning operation. The heads 20 are then righted to a vertical position, the cleaning operation is completed, the bulbs 12 are loaded, and the coating nozzles 22- are reciprocated through the coating chucks 20 and into the bulbs 12. At this point in the operation, the reclaim pinch clamp valve 42 is closed, through opening of the solenoid-actuated valve 84, with the smoke feed pinch clamp valve 40 remaining open. The generated powder smoke is passed into and from the expansion chamber 38, through the open smoke feed pinch clamp valve 40, the distribution manifold 62, and through each of the six delivery conduits 52 which lead to the individual coating heads 33. Thereafter, the coated bulbs are transferred to the conveyor heads 16 and the coating heads 33 tilted from the vertical.

Immediately after the coating operation, and during the initial stages of the apparatus cleaning operation, the reclaim pinch valve 42 is permitted to open by closing solenoid-actuated valve 84. The solenoid-actuated valve 82 is opened to admit cleaning air through the conduit 73 and the ball-check valve 74, and into the distribution manifold 62, and this operation is illustrated in FIG. 6. As shown, most of the air is forced through the expansion chamber 38 and through the open reclaim pinch valve 42, and the actuated reclaim venturi 44 carries the powder back to the powder drum.

In the latter stages of the cleaning operation, the smoke feed pinch clamp valve 40 is closed by opening the solenoid-actuated valve 86, and all cleaning air which is forced into the distribution manifold 62 flows through the smoke delivery conduits '52 to blow residual uncoated powder out of the conduits 52 and the nozzles 22. The solenoid-actuated valve 82 then closes to shut 01f the flow of cleansing air to the distribution manifold 62, the smoke feed pinch valve 40 opens, the coated heads 33 are elevated to the vertical. Both of the solenoid-actuated valves 84 and 86 are three-way valves and when these valves are closed, high-pressure air which closes the pinch-clamp valves 42 and 40 is bled off to the atmosphere, thus permitting the pinch clamp valves 42 and 40 to open.

To complete the cleaning operation, each coating nozzle 22 is then reciprocated a short distance upwardly to a position proximate to a blow-back manifold 88, shown in FIGS. 1 and 2a. Each blow-back manifold 88 is provided with a centrally disposed passageway 90 through which a coating nozzle 22 is reciprocated into coating position. A coating nozzle 22 in position proximate to a blow-back manifold 88- is shown in dotted lines in FIG. 2a. A plurality of apertures 92 open into the central passageway 90 of blow-back manifold 88, and some of these apertures are directed upwardly and some are directed downwardly. The apertures 92 connect to a conduit 94 and when the solenoid-actuated valve 96 is opened, after the nozzle is moved into blow-back position, high-pressure air is directed both upwardly and downwardly. The air which is directed upwardly cleans out the interior portion of the coating chuck 20*. The air which is directed downwardly is forced into the nozzles 22, through the distribution manifolds 5'2, and through the expansion chamber 38. The opposing direction of the cleansing air through the nozzles 22 and the distribution conduits 52 causes a gas-scrubbing action in these components, which insures that all residual powder is removed. Thereafter, the entire bulb transfer, bulb coating, and apparatus cleaning operation are repeated. The coating operations thus comprise the generation of a coating smoke which is delivered to the coating nozzles as -a series of smoke pulses. Between each of these delivered smoke pulses, the coating apparatus is cleaned to remove undeposited large particles and residual, undeposited coating material.

The term large particles as used herein is intended to include agglomerations of particles which are not broken up in the expansion chamber, as well as unitary particles which are too large for coating. In the case of finely divided silica, most of the overly large particles will actuallybe particle agglomerations, as this material is normally very finely divided. Of course, material other than silica can be coated in accordance with the present invention.

Lamps coated in accordance with the present method and apparatus are uniform both in appearance and in thickness of coated material. In addition, lamp rejections because of imperfect coatings have been substantially reduced. This decreased coating shrinkage is due to the removal of overly large silica particle agglomerations from the coating smoke and the complete removal of residual, uncoated powder from the conduits which carry the coating smoke to the coating nozzles. Such residual powder, if not removed, would be coated during a later coating operation.

It will be recognized that the objects of the invention have been achieved by providing an improved method and apparatus for distributing a smoke of finely divided particles to a coating head, or to a plurality of coating heads, while eliminating from the coating smoke any undesired residual particles of coating material and preventing any build-up of uncoated, residual material in the coating lines.

As a possible alternative embodiment, the air-cleansing operations could be reversed in that each nozzle 22 could be placed proximate to a blow-back manifold 88 immediately after the coated bulb was unloaded from the coating chuck 20. Thereafter, the remaining air-cleansing operations would be carried out :as described hereinbefore.

As another possible alternative embodiment, the blowback manifold 88 and the blow-back operation part of the air-cleansing operation could be eliminated, with the aircleansing operation limited to blowing the cleansing air only through the distribution conduit 52 in a direction toward the nozzles 22, and also blowing undeposited powder from the expansion chamber 38. However, the aircleansing operation which utilizes the gas-scrubbing action is more effective and is preferred.

As still another alternative embodiment, more than six bulbs or less than six bulbs could be coated simultaneously with the present method and apparatus.

While a best embodiment of the invention has been illustrated and described in detail, it is to be particularly understood that the invention is not limited thereto or thereby.

We claim as our invention:

1. The method of preventing finely divided solid material, which is formed as a smoke suspended in a gaseous stream and delivered as a series of smoke pulses through a delivery conduit, from settling from one smoke pulse in such delivery conduit and then being picked up by a succeeding smoke pulse, which method comprises:

(a) between passage of smoke pulses through said delivery conduit, forcing a stream of cleansing gas in one direction through said delivery conduit, and

(b) thereafter forcing a stream of cleansing gas through said delivery conduit in a direction opposite to that direction in which cleansing gas was initially forced; whereby the opposing directions in which cleansing gas is forced through said delivery conduit provide a gas-scrubbing action to remove from said delivery conduit any particles previously settled from smoke which has passed through said delivery conduit.

2. The method of preventing finely divided solid material, which is formed as a smoke suspended in a gaseous stream and delivered as a series of smoke pulses through a delivery conduit and then through a nozzle, from settling from one smoke pulse in such delivery conduit and nozzle and then being picked up by a succeeding smoke pulse, which method comprises:

(a) between passage of smoke pulses through said delivery conduit and said nozzle, forcing a stream of cleansing gas into said delivery conduit and then through said nozzle; and

(b) thereafter forcing a stream of cleansing gas into and through said nozzle and then through said delivery conduit; whereby the opposing directions in which cleansing gas is forced through said delivery conduit and said nozzle provide a gas-scrubbing action to remove from said delivery conduit and said nozzle any particles previously settled from smoke which has passed through said delivery conduit and said nozzle.

3. The method of preventing undesired particles of finely divided material from passing through a dispersing nozzle as a part of a smoke of finely divided particles suspended in a gaseous stream and delivered as a series of gaseous pulses, wherein the particle smoke is fed to the dispersing nozzle through a delivery conduit, which method comprises:

(a) expanding into an enclosed volume each pulse of the gaseous stream carrying the particle smoke;

(b) circulating each pulse of the expanded gaseous stream within said enclosed volume to cause the expanded gaseous stream to drop overly large particles from suspension;

(c) forcing particles still in suspension in the expanded gaseous stream through said delivery conduit and through said nozzle; and

(d) between pulses of said gaseous stream carrying the particle smoke, forcing a stream of cleansing gas through said enclosed volume to blow deposited particles therefrom, thereafter forcing a stream of cleansing gas into and through said delivery conduit and then through said nozzle, and thereafter forcing a stream of cleansing gas into and through said nozzle and then through said delivery conduit and said enclosed volume.

4. The method of preventing undesired particles of finely divided material from passing through a dispersing nozzle as part of a smoke of finely divided particles suspended in a gaseous stream and delivered as a series of gaseous pulses, wherein the particle smoke is fed to the dispersing nozzle through a delivery conduit, which method comprises:

(a) expanding into an enclosed volume each pulse of the gaseous stream carrying the particle smoke;

(b) circulating each pulse of the expanded gaseous stream within the enclosed volume to cause the expanded gaseous stream to drop overly large particles from suspension;

(c) forcing particles still in suspension in the expanded gaseous stream through said delivery conduit to said nozzle; and

(d) between pulses of said gaseous stream, forcing a stream of cleansing gas first in one direction through said enclosed volume to remove deposited particles therefrom, and also forcing a stream of cleansing gas in another direction through said feed conduit and then through said nozzle to remove residual particles therefrom.

5. The method of preventing undesired particles of finely divided material, which is formed as part of a particle smoke, from passing through a dispersing nozzle, wherein the smoke is generated as a continuing series of pulses of gaseous material carrying finely divided particles suspended therein, and wherein the smoke is fed through a series of conduits to the dispersing nozzle, which method comprises:

(a) passing a pulse of the initially formed smoke through a feed conduit and into a container, having a volume which is large compared to the feed conduit;

(b) circulating the smoke pulse through said container to cause undesired particles to drop to the bottom portion of said container;

() passing residual smoke from said container and through a delivery conduit connecting to said nozzle;

(d) after the pulse of smoke, forcing cleansing gas through said container to carry therefrom any deposited particles of finely divided material;

(e) thereafter forcing cleansing gas into and through said delivery conduit and out said nozzle to blow deposited finely divided material from said delivery conduit and said nozzle; and

(f) thereafter forcingcleansing gas into and through said nozzle, then through said delivery conduit, and then through said container to insure that all deposited finely divided material is removed from said delivery conduit and said nozzle.

6. The method of preventing undesired particles of finely divided material, which is formed as a part of a particle smoke, from passing through a plurality of dispersing nozzles, wherein the smoke is generated as a continuing series of pulses of gaseous material carrying finely divided particles suspended therein, and wherein the smoke is fed through a series of conduits to the dispersing nozzles, which method comprises:

(a) passing a pulse of the initially formed smoke through a feed conduit and into a container having a volume which is large compared to the feed conduit;

(b) circulating the smoke pulse through said container to cause undesired particles to drop to the bottom portion of said container;

(0) passing residual smoke from said container and through a plurality of delivery conduits each connecting to one of said nozzles;

(d) after the pulse of smoke, forcing air through said container to carry therefrom any deposited particles of finely divided material;

(e) thereafter forcing air into and through said delivery conduits and out said nozzles to blow deposited finely divided material from said delivery conduits and said dispersing nozzles; and

(f) thereafter forcing cleansing gas into and through said nozzles, then through said delivery conduits, and then through said container to insure that all deposited finely divided material is removed from said delivery conduits and said nozzles.

References Cited UNITED STATES PATENTS 1,331,582 2/192'0 Rosenfeld 117-19 1,587,529 6/1926 Hoyt 239-112 2,421,975 3/1943 Williams 117-19 2,642,033 6/1953 Miller 118-308 2,806,444 9/1957 Werner et a1 ll8-49.1 X 2,884,895 5/1959 Lopenski et a1 118-491 3,142,579 7/1964 Brooks 117-18 3,179,341 4/1965 Plos et a1. 239-112 X 0 ALFRED L. LEAVITT, Primary Examiner.

W. L. SOFFIAN, E. B. LIPSCOMB, Assistant Examiners. 

1. THE METHOD OF PREVENTING FINELY DIVIDED SOLID MATERIAL, WHICH IS FORMED AS A SMOKE SUSPENDED IN A GASEOUS STREAM AND DELIVERED AS A SERIES OF SMOKE PULES THROUGH A DELIVERY CONDUIT, FROM SETTING FROM ONE SMOKE PULSE IN SUCH DELIVERY CONDUIT AND THEN BEING PICKED UP BY A SUCCEEDING SMOKE PULSE, WHICH METHOD COMPRISES: (A) BETWEEN PASSAGE OF SMOKE PULES THROUGH SAID DELIVERY CONDUIT, FORCING A STREAM OF CLEANSING GAS IN ONE DIRECTION THROUGH SAID DELIVERY CONDUIT, AND (B) THEREAFTER FORCING A STREAM OF CLEANSING GAS THROUGH SAID DELIVERY CONDUIT IN A DIRECTION OPPOSITE TO THAT DIRECTION IN WHICH CLEANSING GAS WAS INITIALLY FORCED; WHEREBY THE OPPOSING DIRECTIONS IN WHICH CLEANSING GAS IS FORCED THROUGH SAID DELIVERY CONDUIT PROVIDE A GAS-SCRUBBING ACTION TO REMOVE FROM SAID DELIVERY CONDUIT ANY PARTICLES PREVIOUSLY SETTLED FROM SMOKE WHICH HAS PASSED THROUGH SAID DELIVERY CONDUIT.
 3. THE METHOD OF PREVENTING UNDESIRED PARTICLES OF FINELY DIVIDED MATERIAL FROM PASSING THROUGH A DISPERSING NOZZLE AS A PART OF A SMOKE FINELY DIVIDED PARTICLES SUSPENDED IN A GASEOUS STREAM AND DELIVERED AS A SERIES OF GASEOUS PULSES, WHEREIN THE PARTICLE SMOKE IS FED TO THE DISPERSING NOZZLE THROUGH A DELIVERY CONDUIT, WHICH METHOD COMPRISES: (A) EXPANDING INTO AN ENCLOSED VOLUME EACH PULSE OF THE GASEOUS STREAM CARRYING THE PARTICLE SMOKE; (B) CIRCULATING EACH PULSE OF THE EXPANDED GASEOUS STREAM WITHIN SAID ENCLOSED VOLUME TO CAUSE THE EXPANDED GASEOUS STREAM TO DROP OVERLY LARGE PARTICLES FROM SUSPENSION; (C) FORCING PARTICLES STILL IN SUSPENSION IN THE EXPANDED GASEOUS STREAM THROUGH SAID DELIVERY CONDUIT AND THROUGH SAID NOZZLE; AND (D) BETWEEN PULSES OF SAID GASEOUS STREAM CARRYING THE PARTICLE SMOKE, FORCING A STREAM OF CLEANSING GAS THROUGH SAID ENCLOSED VOLUME TO BLOW DEPOSITED PARTICLES THEREFROM, THEREAFTER FORCING A STREAM OF CLEANSING GAS INTO AND THROUGH SAID DELIVERY CONDUIT AND THEN THROUGH SAID NOZZLE, AND THERAFTER FORCING A STREAM OF CLEANSING GAS INTO AND TRHOUGH SAID NOZZLE AND THEN THROUGH SAID DELIVERY CONDUIT AND SAID ENCLOSED VOLUME. 